EP1185144A1 - Hot plate and conductive paste - Google Patents
Hot plate and conductive paste Download PDFInfo
- Publication number
- EP1185144A1 EP1185144A1 EP00922932A EP00922932A EP1185144A1 EP 1185144 A1 EP1185144 A1 EP 1185144A1 EP 00922932 A EP00922932 A EP 00922932A EP 00922932 A EP00922932 A EP 00922932A EP 1185144 A1 EP1185144 A1 EP 1185144A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- grains
- hot plate
- bismuth
- noble metal
- glass frit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000758 substrate Substances 0.000 claims abstract description 59
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 52
- 239000011521 glass Substances 0.000 claims abstract description 40
- 239000000919 ceramic Substances 0.000 claims abstract description 36
- 229910052797 bismuth Inorganic materials 0.000 claims abstract description 30
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910000416 bismuth oxide Inorganic materials 0.000 claims abstract description 25
- TYIXMATWDRGMPF-UHFFFAOYSA-N dibismuth;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Bi+3].[Bi+3] TYIXMATWDRGMPF-UHFFFAOYSA-N 0.000 claims abstract description 25
- 150000004767 nitrides Chemical class 0.000 claims abstract description 8
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 19
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 15
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 15
- 229910052709 silver Inorganic materials 0.000 claims description 15
- 239000004332 silver Substances 0.000 claims description 15
- YGBGWFLNLDFCQL-UHFFFAOYSA-N boron zinc Chemical compound [B].[Zn] YGBGWFLNLDFCQL-UHFFFAOYSA-N 0.000 claims description 13
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 13
- 229910052697 platinum Inorganic materials 0.000 claims description 8
- 229910052763 palladium Inorganic materials 0.000 claims description 7
- 239000010931 gold Substances 0.000 claims description 5
- 239000010942 ceramic carbide Substances 0.000 claims description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052737 gold Inorganic materials 0.000 claims description 4
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 13
- 239000011230 binding agent Substances 0.000 description 12
- 238000000034 method Methods 0.000 description 12
- 229910052581 Si3N4 Inorganic materials 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 10
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 10
- 239000002904 solvent Substances 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 9
- 229910001873 dinitrogen Inorganic materials 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- OAYXUHPQHDHDDZ-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethanol Chemical compound CCCCOCCOCCO OAYXUHPQHDHDDZ-UHFFFAOYSA-N 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 4
- 239000004925 Acrylic resin Substances 0.000 description 3
- 229920000178 Acrylic resin Polymers 0.000 description 3
- 239000001856 Ethyl cellulose Substances 0.000 description 3
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 3
- 229910018879 Pt—Pd Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- CXKCTMHTOKXKQT-UHFFFAOYSA-N cadmium oxide Inorganic materials [Cd]=O CXKCTMHTOKXKQT-UHFFFAOYSA-N 0.000 description 3
- CFEAAQFZALKQPA-UHFFFAOYSA-N cadmium(2+);oxygen(2-) Chemical compound [O-2].[Cd+2] CFEAAQFZALKQPA-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229920001249 ethyl cellulose Polymers 0.000 description 3
- 235000019325 ethyl cellulose Nutrition 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- 230000007261 regionalization Effects 0.000 description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 229910002710 Au-Pd Inorganic materials 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 229910000423 chromium oxide Inorganic materials 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000464 lead oxide Inorganic materials 0.000 description 2
- CJJMLLCUQDSZIZ-UHFFFAOYSA-N oxobismuth Chemical group [Bi]=O CJJMLLCUQDSZIZ-UHFFFAOYSA-N 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 229910001925 ruthenium oxide Inorganic materials 0.000 description 2
- WOCIAKWEIIZHES-UHFFFAOYSA-N ruthenium(iv) oxide Chemical compound O=[Ru]=O WOCIAKWEIIZHES-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- POAOYUHQDCAZBD-UHFFFAOYSA-N 2-butoxyethanol Chemical compound CCCCOCCO POAOYUHQDCAZBD-UHFFFAOYSA-N 0.000 description 1
- ZNQVEEAIQZEUHB-UHFFFAOYSA-N 2-ethoxyethanol Chemical group CCOCCO ZNQVEEAIQZEUHB-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical group CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 1
- 229910002696 Ag-Au Inorganic materials 0.000 description 1
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
- H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
- H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
- H05B3/143—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds applied to semiconductors, e.g. wafers heating
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
- H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
- H05B3/26—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base
- H05B3/265—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base the insulating base being an inorganic material, e.g. ceramic
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/14—Conductive material dispersed in non-conductive inorganic material
- H01B1/16—Conductive material dispersed in non-conductive inorganic material the conductive material comprising metals or alloys
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
- H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
Definitions
- the present invention relates to a hot plate, which uses a ceramic substrate, and a conductive paste.
- a heating apparatus which is referred to as a hot plate, is normally used.
- Substrates made of ceramic, such as alumina are often used to form a hot plate.
- a resistor which functions as a conductive layer and which has a predetermined pattern, is formed on one side of the alumina substrate.
- a terminal connection pad is formed on part of the resistor.
- Such conductive layer is formed by applying, heating, and bonding an alumina substrate silver paste to the substrate. Subsequently, a terminal pin is soldered to the pad, and the terminal pin is connected to a power source by a wire.
- a silicon wafer, which is a heated subject is placed on an upper surface of the hot plate. When the resistor is energized in this state, the silicon wafer is heated to 100°C or higher.
- a conductive paste including 60wt% to 80wt% of silver, 1wt% to 10wt% of glass frit, the base of which is lead boron silicate, 1wt% to 10wt% of a binder, and 10wt% to 30wt% of a solvent is often used to form a conductive pattern layer (refer to Japanese Unexamined Patent Publication No. 4-300249).
- Glass frit, which is a secondary component, is especially required to obtain the optimal adhesion for the conductive pattern layer.
- the heat produced when bonding the paste causes the oxides in the paste to react with the ceramic and if, for example, the ceramic is aluminum nitride, produces a large amount of gases, such as nitrogen gas. This is considered to occur mainly because of the large amount of lead oxide in the glass frit.
- the high pressure of the nitrogen gas produced during the bonding of the paste forces the nitrogen gas to pass through the grain boundary of the silver grains toward the exterior of the conductive pattern layer.
- the conductive pattern layer is apt to expand and the accuracy for forming the pattern decreases.
- a first perspective of the present invention provides a hot plate using a ceramic substrate provided with a conductive layer.
- the conductive layer includes bismuth or bismuth oxide, glass frit, and noble metal grains. Accordingly, the conductive layer includes bismuth or bismuth oxide, which are relatively easily oxidized and reduced in comparison to oxides that are included in the glass frit. In a conductive layer that includes such substance, expansion is suppressed even if the amount of added glass frit is large. Further, the increase in the amount of added glass frit (the added amount being 1wt% or greater relative to the noble metal grains) improves the adhesion of the conductive layer.
- a second perspective of the present invention is a hot plate having a conductive layer in which the content of bismuth or bismuth oxide is 18wt% or less. If the content exceeds 18wt%, the bismuth oxide noble metal grains are separated. This would result in non-uniform resistance.
- a third perspective of the present invention is a hot 'plate in which a ceramic substrate is a ceramic nitride substrate or a ceramic carbide substrate.
- the ceramic nitride substrate or the ceramic carbide substrate has superior thermal conductivity and tends to react with glass frit and produce gases.
- an aluminum nitride substrate which has especially superior heat resistance and high thermal conductivity among the ceramic nitride substrates, a hot plate that can withstand usage under high temperatures is produced.
- a silicon carbide substrate may be used as the ceramic carbide substrate.
- a fourth perspective of the present invention is a hot plate having a conductive layer that contains glass frit, which includes zinc boron silicate.
- Glass frit including zinc boron silicate reacts with the nitride or the carbide in the ceramic substrate and produces nitrogen gas. Further, it is assumed that bismuth or bismuth oxide suppresses such reaction. Accordingly, a large amount of gas is not produced and expansion of the conductive layer does not occur even if a conductive layer made from a material using this component is employed.
- a fifth perspective of the present invention is a hot plate provided with a conductive layer including noble metal grains selected from at least one of gold grains, silver grains, platinum grains, and palladium grains.
- the gold grains, silver grains, platinum grains, and palladium grains relatively resist oxidization even when exposed to high temperatures and have a sufficiently large resistance.
- the optimal conductive layer which serves as a heating resistor, is easily produced.
- a sixth perspective of the present invention is a hot plate having a conductive layer formed from bismuth or bismuth oxide, glass frit, noble metal grains, and an organic vehicle.
- a seventh perspective of the present invention is a hot plate in which the content of the bismuth or bismuth oxide in the conductive layer is 18% or less.
- Fig. 1 is a schematic cross-sectional view showing a hot plate unit according to one embodiment of the present invention.
- Fig. 2 is a partial enlarged cross-sectional view showing the hot plate unit of Fig. 2.
- a hot plate unit 1 according to one embodiment of the present invention will now be described with reference to Figs. 1 and 2.
- the hot plate unit 1 which is shown in Fig. 1, includes a casing 2 and a hot plate 3.
- the casing 2 is a cup-like metal member having an opened portion 4, the cross-section of which is round, located at its upper portion.
- the casing 2 does not have to be cup-like and may have an opened bottom.
- a hot plate 3 is attached to the opening 4 by means of a seal ring 14.
- a lead wire hole 7 for receiving current supplying lead wires 6 extends through the peripheral part of the bottom portion 2a of the casing 2.
- the hot plate 3 of the present embodiment which is formed from a ceramic substrate 9, is a low-temperature hot plate 3 used to dry a silicon wafer W1, to which a photosensitive resin is applied, at 50°C to 300°C.
- a ceramic nitride substrate be selected as the ceramic substrate 9 since it has superior heat resistance and high thermal conductivity properties. More specifically, it is preferred that an aluminum nitride substrate, a silicon nitride substrate, a boron nitride substrate, or a titanium nitride substrate be selected. Among these substrates, it is most preferred that the aluminum nitride substrate be selected and next preferred that the silicon nitride substrate be selected. This is because these substrates have the highest thermal conductivity among the above ceramic nitrides.
- the ceramic substrate 9 is disk-like, has a thickness of about 1mm to 100mm, and has a diameter that is slightly smaller than the outer dimension of the casing 2.
- a wiring resistor 10 which serves as a conductive pattern layer, is formed in a concentric or spiral manner on the lower surface of the plate-like substrate 9.
- Pads 10a are formed on an end of the wiring resistor 10.
- the wiring resistor 10 and the pads 10a are formed by printing, heating, and bonding a conductive paste (noble metal paste) P1 on the surface of the ceramic substrate 9.
- the surface for heating the silicon wafer W1 is located on the opposite side of the conductive pattern layer formation layer, or on the upper surface.
- Such structure has an advantage in that a difference in temperature between locations does not occur in the hot plate 3 and in that the silicon wafer W1 is uniformly heated.
- the wiring resistor 10 and the pads 10a of the present embodiment that are formed from the noble metal paste P1 includes noble metal grains as a main component and glass frit, or the like, as a secondary component. It is preferred that the noble metal grains used in the present embodiment have an average grain diameter of 6 ⁇ m or less and be flake-like.
- the flake-like noble metal grains be selected from one of gold grains (Au grains), silver grains (Ag grains), platinum grains (Pt grains), and palladium grains (Pd grains). These noble metals relatively resist oxidation even if they are exposed to high temperatures and have a sufficiently large resistance when energized and heated. These noble metals may be used alone or by combining two, three, or four of these metals as described below. The combinations include Ag-Au, Ag-Pt, Ag-Pd, Au-Pt, Au-Pd, Pt-Pd, Ag-Au-Pt, Ag-Au-Pd, Ag-Au-Pt, Au-Pt-Pd, Ag-Au-Pt-Pd.
- a terminal pin 12 which is made of a conductive material, is soldered to each pad 10a. This electrically connects each terminal pin 12 to the wiring resistor 10. Sockets 6a, which are located on the distal end of the lead wires 6, are fit into the distal ends of the terminal pins 12. Accordingly, the temperature of the wiring resistor 10 increases and heats the entire hot plate 3 when current is supplied to the wiring resistor 10 via the lead wires 6 and the terminal pins 12.
- a sintering-aid agent such as yttria, and a binder are added as required to ceramic grains to prepare a mixture.
- the mixture is uniformly kneaded into three rolls.
- the kneaded material is used to press mold plate-like molding products having a thickness of 1 to 100mm.
- the molded product is dried. Then, the molded product undergoes provisional baking and main baking so that it is completely sintered. This forms the ceramic sinter substrate 9. It is preferred that the baking process be performed in a hot-press apparatus and that the baking process be performed at a temperature of about 1500°C to 2000°C. Afterward, the ceramic substrate 9 is cut into a disk-like shape having a predetermined diameter (in the present embodiment, 230mm ⁇ ) and undergoes surface grinding with a hub grinder.
- a predetermined diameter in the present embodiment, 230mm ⁇
- the noble metal paste P1 which has been prepared beforehand, is uniformly applied to the lower surface of the ceramic substrate 9, preferably through screen-printing.
- the noble metal paste P1 used here includes ruthenium oxide, glass frit, a resin binder, and a solvent.
- the noble metal paste P1 may also include bismuth or bismuth oxide.
- the reason for adding bismuth (Bi) or bismuth oxide (Bi 2 O 3 ) to the noble metal paste P1 is as follows. Test results have shown that by adding these substances, reaction between the glass frit and the aluminum nitride or the silicon carbide is suppressed and the adhesion of the wiring resistor 10 and the pads 10a is increased. These substances are relatively easily oxidized and reduced in comparison to other oxides. It is presently presumed that such properties contribute in one way or another to suppress expansion and enhance adhesion.
- bismuth oxide reacts with the aluminum nitride when the paste is bonded and produces alumina and nitrogen gas.
- the bismuth oxide functions as an oxidization agent of the aluminum nitride.
- bismuth is easily oxidized into bismuth oxide.
- bismuth may considered as an indirect oxidization agent of the aluminum nitride.
- bismuth oxide when selecting, for example, silicon nitride as the substrate material, bismuth oxide reacts with silicon nitride when the paste is bonded and produces silica and nitrogen gas. Thus, the bismuth oxide functions as an oxidization agent of the silicon nitride. In the same manner, bismuth may be considered as an oxidization agent of the silicon nitride.
- the noble metal paste P1 it is preferred that about 0.1wt% to 10wt% of bismuth or bismuth oxide be included in the noble metal paste P1, more preferred that about 1wt% to 5wt% be included, and especially preferred that about 2wt% to 3wt% be included. If the content of bismuth or bismuth oxide is too small, the effect obtaining by adding bismuth or bismuth is insufficient. Thus, the expansion may not be prevented and the adhesion may not be significantly improved. On the other hand, if the content of bismuth and bismuth oxide is too large, reaction that generates nitrogen gas increases. This may increase expansion.
- the amount of glass frit be a fraction of the amount of noble metal grains. This is because such amount of the glass frit component in the noble metal paste does not generate much nitrogen gas and the adhesion of the wiring resistor 10 and the pads 10a do not decrease. Further, as the amount of a conductive component in the noble metal paste P1 increases, the specific resistance of the wiring resistor 10 may be decreased. Specifically, in the present embodiment, 60wt% to 80wt% of noble metal grains and 1wt% to 10wt% of glass frit is included in the noble metal paste P1.
- glass frit including zinc boron silicate (SiO 2 : B 2 O 3 : ZnO 2 ) be used, and especially preferred that the glass frit includes zinc boron silicate as a base (i.e., main component). More specifically, it is preferred that a small amount of oxide be added to the zinc boron silicate, which serves as a base.
- oxides include aluminum oxide (Al 2 O 3 ), yttrium oxide (Y 2 O 3 ), lead oxide (PbO), cadmium oxide (CdO), chromium oxide (Cr 2 O 3 ), and copper oxide (CuO).
- oxides or a combination of two or more of these oxides may be added to the zinc boron silicate. During the bonding of the paste, these oxides function as an oxidization agent of the substrate material and are thus reduced.
- the weight ratio of each of the above listed oxides be 1/20 times to 1/5 times the weight ratio of zinc boron silicate. If the weight ratio is too small, the percentage of the above oxides in the glass frit increases. As a result, the expansion caused by nitrogen gas may not be sufficiently prevented. On the other hand, if the weight ratio is too large, the percentage of the above oxides in the glass frit decreases. As a result, the adhesion of the wiring resistor 10 may not be sufficiently increased.
- the noble metal paste P1 also includes 3wt% to 15wt% of a resin binder, which serves as an organic vehicle, and 10wt% to 30wt% of a solvent.
- a resin binder which serves as an organic vehicle
- 10wt% to 30wt% of a solvent examples of the resin binder are, for example, the cellulose group such as ethyl cellulose.
- the solvent is a component added to improve the printing and dispersion characteristics. Specific examples of the solvent are the acetate group, the cellosolve group such as butyl cellosolve, or the Carbitol group such as butyl Carbitol. One or a combination of two or more of these solvents may be used.
- the solvent in the noble metal paste P1 volatilizes and bonds the wiring resistor 10 and the pads 10a to the ceramic substrate 9.
- Fused glass frit has a tendency to move toward the surface of the ceramic substrate 9.
- the noble metal grains have a tendency to move away from the surface of the ceramic substrate 9.
- the pads 10a are connected to the terminal pins 12 by a solder S1 to complete the hot plate 3.
- the hot plate 3 is attached to the opening 4 of the casing 2 to complete the desired hot plate unit 1 of Fig. 1.
- the resistor of the hot plate unit 1 does not expand and has high tensile strength. Further, the difference in the resistance of the resistor is small. This uniformly heats the heating surface of the hot plate.
- examples 1 to 5 and comparative examples 1 to 3 4 parts by weight of Y 2 O 3 (average grain diameter 0.4 ⁇ m) and 8 parts by weight of an acrylic resin binder (manufactured by Mitsui Chemicals, product name: SA-545, acid number 1.0) were added to 100 parts by weight of aluminum nitride powder (average grain diameter 1.1 ⁇ m) and mixed. The mixture produced in this manner was uniformly kneaded. The kneaded product was put into a press mold and pressed to form a plate-like molded product.
- an acrylic resin binder manufactured by Mitsui Chemicals, product name: SA-545, acid number 1.0
- the molded product was degreased in a nitrogen atmosphere for four hours at a temperature of 350°C for four hours to thermally decompose the binder. Further, the degreased molded body was baked in a hot-press for three hours at a temperature of 1600°C to produce an aluminum nitride substrate. The pressure of the hot press was 150kg/cm 2 .
- a paste applying process was performed.
- the noble metal paste P1 the composition of which is described below, was used and applied to a thickness of about 25 ⁇ m. Eight types of samples were prepared in accordance with the above procedure (refer to table 1).
- noble metal grains Only one type of noble metal grains, that is, silver grains, which were flake-like and had an average grain diameter of 5 ⁇ m, was used.
- the added amount of the silver grains in the silver paste, which served as the noble metal paste P1 was 65wt% in samples 2 and 7 and 70wt% in the other samples.
- glass frit including zinc boron silicate as a base (i.e., a zinc-containing material was used as the glass frit) and one type of glass frit including lead boron silicate (i.e., a lead containing material) was prepared.
- the specific compositions of zinc glass frits ⁇ , ⁇ , ⁇ , ⁇ are each shown in the lower rows of table 1.
- the amount of each glass frit added to the noble metal paste is as shown in table 1.
- the added amount of bismuth in samples 1, 3, 4, and 5 (i.e., examples 1, 3, 4, and 5) is set at 3wt%
- the added amount of bismuth in sample 2 i.e., example 2
- the added amount of bismuth in the other samples is set at 0wt%.
- Ethyl cellulose was selected as the binder, and butyl Carbitol was selected as the solvent.
- the added amount of ethyl cellulose was 5wt% and the added amount of noble metal paste P1 was 15wt%.
- samples 6 to 8 correspond to comparative examples 1 to 3.
- example 6 45 parts by weight of Y 2 O 3 (average grain diameter 0.4 ⁇ m), 15 parts by weight of Al 2 O 3 (average grain diameter 0.5 ⁇ m), 20 parts by weight of SiO 2 (average grain diameter 0.5 ⁇ m), and 8 parts by weight of an acrylic resin binder (manufactured by Mitsui Chemicals, product name: SA-545, acid number 1.0) were mixed with 45 parts by weight of silicon nitride powder (average grain diameter 1.1 ⁇ m).
- an acrylic resin binder manufactured by Mitsui Chemicals, product name: SA-545, acid number 1.0
- the mixture obtained in this manner was uniformly kneaded.
- the kneaded product was put into a press mold and pressed to form a plate-like molded product.
- the molded product was degreased for four hours at a temperature of 350°C for four hours in a nitrogen atmosphere to thermally decompose the binder. Further, the degreased molded body was baked in a hot-press for three hours at a temperature of 1600°C to produce a silicon nitride substrate, or the ceramic substrate 9. The pressure of the hot press was 150kg/cm 2 .
- a paste applying process was performed.
- the noble metal paste P1 the composition of which is described below, was used and applied to a thickness of about 25 ⁇ m to form sample 9.
- Bismuth oxide was used instead of bismuth.
- the applied noble metal paste P1 was heated at a temperature of about 750°C for a predetermined time to bond the wiring resistor 10 and the pads 10a and complete the hot plate 3 of example 6.
- examples 7 and 8 0.5 parts by weight of C (carbon) and 8 parts by weight of an acrylic resin binder (manufactured by Mitsui Chemicals, product name: SA-545, acid number 1.0) were mixed with 45 parts by weight of silicon carbide powder (average grain diameter 1.1 ⁇ m).
- the mixture obtained in this manner was uniformly kneaded.
- the kneaded product was put into a press mold and pressed to form a plate-like molded product.
- the molded product was degreased.for four hours at a temperature of 350°C for four hours in a nitrogen atmosphere to thermally decompose the binder. Further, the degreased molded body was baked in a hot-press for three hours at a temperature of 900°C to produce a silicon nitride substrate, or the ceramic substrate 9. The pressure of the hot press was 150kg/cm 2 .
- a paste applying process was performed using the noble metal paste P1 (i.e., pastes A and B), the composition of which is described below to form samples 10 and 11 (examples 7 and 8).
- Spherical noble metal grains may be used in lieu of the flake-like noble metal grains. Further, instead of using only one type of the noble metal grains, two or more types of noble metal grains (e.g., flake-like grains and spherical grains) may be mixed and used.
- the ceramic substrate 9, which is formed from aluminum nitride or silicon nitride, is not limited to products manufactured through press molding and may be manufactured, for example, by performing sheet molding with a doctor blade apparatus.
- the wiring resistor 10 may, for example, be arranged between superimposed sheets.
- the high temperature hot plate 3 is manufactured in a relatively simple manner.
- the conductive pattern layer is not limited to the wiring resistor 10 and the pads 10a used in the above embodiment and may be other structures such as a conductive pattern layer that is not a heating resistor.
- the noble metal paste P1 need not be screen printed on the ceramic substrate 9.
- the noble metal paste P1 may be stamped on the ceramic substrate 9.
- the above oxides do not have to be included in the noble metal paste P1 separately from glass frit and may be included in the noble metal paste P1 in a state in which the oxide is added to the glass frit as a secondary component of the glass frit. Oxides included in the glass frit as a secondary component is more preferred since such oxide is uniformly dispersed in the noble metal paste P1.
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Abstract
A hot plate having a conductive pattern layer that
does not expand much and has superior adhesion. The hot
plate (3) has a conductive pattern layer (10, 10a) arranged
on a ceramic nitride substrate (9). The conductive pattern
layer (10, 10a) includes bismuth or bismuth oxide, glass
frit, and noble metal grains.
Description
The present invention relates to a hot plate, which
uses a ceramic substrate, and a conductive paste.
During a semiconductor fabrication process, for
example, when heating and drying a silicon wafer subsequent
to the application of a photosensitive resin, a heating
apparatus, which is referred to as a hot plate, is normally
used.
Substrates made of ceramic, such as alumina, are often
used to form a hot plate. A resistor, which functions as a
conductive layer and which has a predetermined pattern, is
formed on one side of the alumina substrate. A terminal
connection pad is formed on part of the resistor. Such
conductive layer is formed by applying, heating, and bonding
an alumina substrate silver paste to the substrate.
Subsequently, a terminal pin is soldered to the pad, and the
terminal pin is connected to a power source by a wire. A
silicon wafer, which is a heated subject, is placed on an
upper surface of the hot plate. When the resistor is
energized in this state, the silicon wafer is heated to
100°C or higher.
A conductive paste including 60wt% to 80wt% of silver,
1wt% to 10wt% of glass frit, the base of which is lead boron
silicate, 1wt% to 10wt% of a binder, and 10wt% to 30wt% of a
solvent is often used to form a conductive pattern layer
(refer to Japanese Unexamined Patent Publication No. 4-300249).
Glass frit, which is a secondary component, is
especially required to obtain the optimal adhesion for the
conductive pattern layer.
When applying the above conventional lead paste
directly to a ceramic substrate, the following shortcomings
occur. The heat produced when bonding the paste causes the
oxides in the paste to react with the ceramic and if, for
example, the ceramic is aluminum nitride, produces a large
amount of gases, such as nitrogen gas. This is considered to
occur mainly because of the large amount of lead oxide in
the glass frit. In this case, the high pressure of the
nitrogen gas produced during the bonding of the paste forces
the nitrogen gas to pass through the grain boundary of the
silver grains toward the exterior of the conductive pattern
layer. As a result, the conductive pattern layer is apt to
expand and the accuracy for forming the pattern decreases.
If the amount of glass frit added to the paste is
decreased to an extremely low level, the undesirable effects
of the lead oxide is reduced. This suppresses expansion for
a certain degree. On the other hand, this increases the
possibility of the conductive pattern having lower adhesion.
It is an object of the present invention to provide a
hot plate having a conductive pattern layer that expands
little, has superior adhesion, and has a large specific
resistance and to provide a conductive paste optimal for the
manufacturing of such hot plate.
To achieve the above object, a first perspective of
the present invention provides a hot plate using a ceramic
substrate provided with a conductive layer. The conductive
layer includes bismuth or bismuth oxide, glass frit, and
noble metal grains. Accordingly, the conductive layer
includes bismuth or bismuth oxide, which are relatively
easily oxidized and reduced in comparison to oxides that are
included in the glass frit. In a conductive layer that
includes such substance, expansion is suppressed even if the
amount of added glass frit is large. Further, the increase
in the amount of added glass frit (the added amount being
1wt% or greater relative to the noble metal grains) improves
the adhesion of the conductive layer.
A second perspective of the present invention is a hot
plate having a conductive layer in which the content of
bismuth or bismuth oxide is 18wt% or less. If the content
exceeds 18wt%, the bismuth oxide noble metal grains are
separated. This would result in non-uniform resistance.
A third perspective of the present invention is a hot
'plate in which a ceramic substrate is a ceramic nitride
substrate or a ceramic carbide substrate. The ceramic
nitride substrate or the ceramic carbide substrate has
superior thermal conductivity and tends to react with glass
frit and produce gases. By using an aluminum nitride
substrate, which has especially superior heat resistance and
high thermal conductivity among the ceramic nitride
substrates, a hot plate that can withstand usage under high
temperatures is produced. Further, a silicon carbide
substrate may be used as the ceramic carbide substrate.
A fourth perspective of the present invention is a hot
plate having a conductive layer that contains glass frit,
which includes zinc boron silicate. Glass frit including
zinc boron silicate reacts with the nitride or the carbide
in the ceramic substrate and produces nitrogen gas. Further,
it is assumed that bismuth or bismuth oxide suppresses such
reaction. Accordingly, a large amount of gas is not produced
and expansion of the conductive layer does not occur even if
a conductive layer made from a material using this component
is employed.
A fifth perspective of the present invention is a hot
plate provided with a conductive layer including noble metal
grains selected from at least one of gold grains, silver
grains, platinum grains, and palladium grains. The gold
grains, silver grains, platinum grains, and palladium grains
relatively resist oxidization even when exposed to high
temperatures and have a sufficiently large resistance. Thus,
the optimal conductive layer, which serves as a heating
resistor, is easily produced.
A sixth perspective of the present invention is a hot
plate having a conductive layer formed from bismuth or
bismuth oxide, glass frit, noble metal grains, and an
organic vehicle.
A seventh perspective of the present invention is a
hot plate in which the content of the bismuth or bismuth
oxide in the conductive layer is 18% or less.
Fig. 1 is a schematic cross-sectional view showing a
hot plate unit according to one embodiment of the present
invention.
Fig. 2 is a partial enlarged cross-sectional view
showing the hot plate unit of Fig. 2.
A hot plate unit 1 according to one embodiment of the
present invention will now be described with reference to
Figs. 1 and 2.
The hot plate unit 1, which is shown in Fig. 1,
includes a casing 2 and a hot plate 3.
The casing 2 is a cup-like metal member having an
opened portion 4, the cross-section of which is round,
located at its upper portion. The casing 2 does not have to
be cup-like and may have an opened bottom. A hot plate 3 is
attached to the opening 4 by means of a seal ring 14. A lead
wire hole 7 for receiving current supplying lead wires 6
extends through the peripheral part of the bottom portion 2a
of the casing 2.
The hot plate 3 of the present embodiment, which is
formed from a ceramic substrate 9, is a low-temperature hot
plate 3 used to dry a silicon wafer W1, to which a
photosensitive resin is applied, at 50°C to 300°C.
It is preferred that a ceramic nitride substrate be
selected as the ceramic substrate 9 since it has superior
heat resistance and high thermal conductivity properties.
More specifically, it is preferred that an aluminum nitride
substrate, a silicon nitride substrate, a boron nitride
substrate, or a titanium nitride substrate be selected.
Among these substrates, it is most preferred that the
aluminum nitride substrate be selected and next preferred
that the silicon nitride substrate be selected. This is
because these substrates have the highest thermal
conductivity among the above ceramic nitrides.
The ceramic substrate 9 is disk-like, has a thickness
of about 1mm to 100mm, and has a diameter that is slightly
smaller than the outer dimension of the casing 2.
Referring to Figs. 1 and 2, a wiring resistor 10,
which serves as a conductive pattern layer, is formed in a
concentric or spiral manner on the lower surface of the
plate-like substrate 9. Pads 10a are formed on an end of the
wiring resistor 10. The wiring resistor 10 and the pads 10a
are formed by printing, heating, and bonding a conductive
paste (noble metal paste) P1 on the surface of the ceramic
substrate 9. In the hot plate 3 of the present embodiment,
the surface for heating the silicon wafer W1 is located on
the opposite side of the conductive pattern layer formation
layer, or on the upper surface. Such structure has an
advantage in that a difference in temperature between
locations does not occur in the hot plate 3 and in that the
silicon wafer W1 is uniformly heated.
The wiring resistor 10 and the pads 10a of the present
embodiment that are formed from the noble metal paste P1
includes noble metal grains as a main component and glass
frit, or the like, as a secondary component. It is preferred
that the noble metal grains used in the present embodiment
have an average grain diameter of 6µm or less and be flake-like.
It is preferred that the flake-like noble metal grains
be selected from one of gold grains (Au grains), silver
grains (Ag grains), platinum grains (Pt grains), and
palladium grains (Pd grains). These noble metals relatively
resist oxidation even if they are exposed to high
temperatures and have a sufficiently large resistance when
energized and heated. These noble metals may be used alone
or by combining two, three, or four of these metals as
described below. The combinations include Ag-Au, Ag-Pt, Ag-Pd,
Au-Pt, Au-Pd, Pt-Pd, Ag-Au-Pt, Ag-Au-Pd, Ag-Au-Pt, Au-Pt-Pd,
Ag-Au-Pt-Pd.
Referring to Figs. 1 and 2, the basal end of a
terminal pin 12, which is made of a conductive material, is
soldered to each pad 10a. This electrically connects each
terminal pin 12 to the wiring resistor 10. Sockets 6a, which
are located on the distal end of the lead wires 6, are fit
into the distal ends of the terminal pins 12. Accordingly,
the temperature of the wiring resistor 10 increases and
heats the entire hot plate 3 when current is supplied to the
wiring resistor 10 via the lead wires 6 and the terminal
pins 12.
An example of the procedures for manufacturing the hot
plate 3 will now be briefly described.
A sintering-aid agent, such as yttria, and a binder
are added as required to ceramic grains to prepare a mixture.
The mixture is uniformly kneaded into three rolls. The
kneaded material is used to press mold plate-like molding
products having a thickness of 1 to 100mm.
Holes are punched or drilled in the molded product to
form pin insertion holes, which are not shown in the
drawings. After the hole forming process, the molded product
is dried. Then, the molded product undergoes provisional
baking and main baking so that it is completely sintered.
This forms the ceramic sinter substrate 9. It is preferred
that the baking process be performed in a hot-press
apparatus and that the baking process be performed at a
temperature of about 1500°C to 2000°C. Afterward, the
ceramic substrate 9 is cut into a disk-like shape having a
predetermined diameter (in the present embodiment, 230mmΦ)
and undergoes surface grinding with a hub grinder.
After the above process, the noble metal paste P1,
which has been prepared beforehand, is uniformly applied to
the lower surface of the ceramic substrate 9, preferably
through screen-printing.
In addition to noble metal grains, the noble metal
paste P1 used here includes ruthenium oxide, glass frit, a
resin binder, and a solvent. The noble metal paste P1 may
also include bismuth or bismuth oxide.
The reason for adding bismuth (Bi) or bismuth oxide
(Bi2O3) to the noble metal paste P1 is as follows. Test
results have shown that by adding these substances, reaction
between the glass frit and the aluminum nitride or the
silicon carbide is suppressed and the adhesion of the wiring
resistor 10 and the pads 10a is increased. These substances
are relatively easily oxidized and reduced in comparison to
other oxides. It is presently presumed that such properties
contribute in one way or another to suppress expansion and
enhance adhesion.
When selecting, for example, aluminum nitride, as the
substrate material, bismuth oxide reacts with the aluminum
nitride when the paste is bonded and produces alumina and
nitrogen gas. Thus, the bismuth oxide functions as an
oxidization agent of the aluminum nitride. Further, when
exposed to air, bismuth is easily oxidized into bismuth
oxide. Thus, bismuth may considered as an indirect
oxidization agent of the aluminum nitride.
Additionally, when selecting, for example, silicon
nitride as the substrate material, bismuth oxide reacts with
silicon nitride when the paste is bonded and produces silica
and nitrogen gas. Thus, the bismuth oxide functions as an
oxidization agent of the silicon nitride. In the same manner,
bismuth may be considered as an oxidization agent of the
silicon nitride.
It is preferred that about 0.1wt% to 10wt% of bismuth
or bismuth oxide be included in the noble metal paste P1,
more preferred that about 1wt% to 5wt% be included, and
especially preferred that about 2wt% to 3wt% be included. If
the content of bismuth or bismuth oxide is too small, the
effect obtaining by adding bismuth or bismuth is
insufficient. Thus, the expansion may not be prevented and
the adhesion may not be significantly improved. On the other
hand, if the content of bismuth and bismuth oxide is too
large, reaction that generates nitrogen gas increases. This
may increase expansion.
It is preferred that the amount of glass frit be a
fraction of the amount of noble metal grains. This is
because such amount of the glass frit component in the noble
metal paste does not generate much nitrogen gas and the
adhesion of the wiring resistor 10 and the pads 10a do not
decrease. Further, as the amount of a conductive component
in the noble metal paste P1 increases, the specific
resistance of the wiring resistor 10 may be decreased.
Specifically, in the present embodiment, 60wt% to 80wt% of
noble metal grains and 1wt% to 10wt% of glass frit is
included in the noble metal paste P1.
It is preferred that glass frit including zinc boron
silicate (SiO2: B2O3: ZnO2) be used, and especially preferred
that the glass frit includes zinc boron silicate as a base
(i.e., main component). More specifically, it is preferred
that a small amount of oxide be added to the zinc boron
silicate, which serves as a base. Specific examples of
oxides include aluminum oxide (Al2O3), yttrium oxide (Y2O3),
lead oxide (PbO), cadmium oxide (CdO), chromium oxide (Cr2O3),
and copper oxide (CuO). One of these oxides or a combination
of two or more of these oxides may be added to the zinc
boron silicate. During the bonding of the paste, these
oxides function as an oxidization agent of the substrate
material and are thus reduced.
It is preferred that the weight ratio of each of the
above listed oxides be 1/20 times to 1/5 times the weight
ratio of zinc boron silicate. If the weight ratio is too
small, the percentage of the above oxides in the glass frit
increases. As a result, the expansion caused by nitrogen gas
may not be sufficiently prevented. On the other hand, if the
weight ratio is too large, the percentage of the above
oxides in the glass frit decreases. As a result, the
adhesion of the wiring resistor 10 may not be sufficiently
increased.
The noble metal paste P1 also includes 3wt% to 15wt%
of a resin binder, which serves as an organic vehicle, and
10wt% to 30wt% of a solvent. Examples of the resin binder
are, for example, the cellulose group such as ethyl
cellulose. The solvent is a component added to improve the
printing and dispersion characteristics. Specific examples
of the solvent are the acetate group, the cellosolve group
such as butyl cellosolve, or the Carbitol group such as
butyl Carbitol. One or a combination of two or more of these
solvents may be used.
When the noble metal paste P1 applied to the ceramic
substrate 9 is heated for a predetermined time at a
temperature of about 750°C, the solvent in the noble metal
paste P1 volatilizes and bonds the wiring resistor 10 and
the pads 10a to the ceramic substrate 9. Fused glass frit
has a tendency to move toward the surface of the ceramic
substrate 9. Contrarily, the noble metal grains have a
tendency to move away from the surface of the ceramic
substrate 9.
Subsequently, the pads 10a are connected to the
terminal pins 12 by a solder S1 to complete the hot plate 3.
Then, the hot plate 3 is attached to the opening 4 of the
casing 2 to complete the desired hot plate unit 1 of Fig. 1.
Thus, the resistor of the hot plate unit 1 does not expand
and has high tensile strength. Further, the difference in
the resistance of the resistor is small. This uniformly
heats the heating surface of the hot plate.
In examples 1 to 5 and comparative examples 1 to 3, 4
parts by weight of Y2O3 (average grain diameter 0.4µm) and 8
parts by weight of an acrylic resin binder (manufactured by
Mitsui Chemicals, product name: SA-545, acid number 1.0)
were added to 100 parts by weight of aluminum nitride powder
(average grain diameter 1.1µm) and mixed. The mixture
produced in this manner was uniformly kneaded. The kneaded
product was put into a press mold and pressed to form a
plate-like molded product.
Then, after forming holes and performing a drying
process, the molded product was degreased in a nitrogen
atmosphere for four hours at a temperature of 350°C for four
hours to thermally decompose the binder. Further, the
degreased molded body was baked in a hot-press for three
hours at a temperature of 1600°C to produce an aluminum
nitride substrate. The pressure of the hot press was
150kg/cm2.
Then, after cutting the substrate and performing
surface grinding, a paste applying process was performed. In
the process, the noble metal paste P1, the composition of
which is described below, was used and applied to a
thickness of about 25µm. Eight types of samples were
prepared in accordance with the above procedure (refer to
table 1).
Only one type of noble metal grains, that is, silver
grains, which were flake-like and had an average grain
diameter of 5µm, was used. The added amount of the silver
grains in the silver paste, which served as the noble metal
paste P1, was 65wt% in samples 2 and 7 and 70wt% in the
other samples.
Four types of glass frit including zinc boron silicate
as a base (i.e., a zinc-containing material was used as the
glass frit) and one type of glass frit including lead boron
silicate (i.e., a lead containing material) was prepared.
The specific compositions of zinc glass frits α, β, γ, δ are
each shown in the lower rows of table 1. The amount of each
glass frit added to the noble metal paste is as shown in
table 1.
The added amount of bismuth in samples 1, 3, 4, and 5
(i.e., examples 1, 3, 4, and 5) is set at 3wt%, the added
amount of bismuth in sample 2 (i.e., example 2) is set at
2wt%, and the added amount of bismuth in the other samples
(comparative examples 1, 2, 3) is set at 0wt%.
Ethyl cellulose was selected as the binder, and butyl
Carbitol was selected as the solvent. The added amount of
ethyl cellulose was 5wt% and the added amount of noble metal
paste P1 was 15wt%.
Although bismuth was added, ruthenium oxide was not
added in samples 6, 7, and 8. Thus, samples 6, 7, 8 do not
satisfy the optimal conditions of the present embodiment.
Further, in sample 8, the amount of glass frit is small in
comparison to the amount of silver grains. Thus, sample 8
does not satisfy the optimal conditions of the present
embodiment. Accordingly, samples 1 to 5 correspond to
examples 1 to 5, and samples 6 to 8 correspond to
comparative examples 1 to 3.
In each of the eight samples, the paste was printed to
and bonded on the ceramic substrate 9, and two square
millimeter test patterns were formed at multiple locations.
A tensile strength test was performed on test patterns that
did not expand, and the average value of the measured values
(kgf/2mm□) was calculated. The expansion of the test
patterns was confirmed through observation with the naked
eye and with an optical microscope. Further, voltage was
applied to increase the temperature of the samples to 180°C.
Then, the difference (°C) between the maximum temperature
and the minimum temperature in the heating surface was
confirmed with a thermo-viewer (IR-62012-0012, manufactured
by Nihon Datum). The results of the tests are shown in table
1.
Sample No. | Grains (wt%) | Added Amount of Bi or its oxide (wt%) | Type and Added Amount of Glass Frit (wt%) | Expansion | Tensile Strength (kgf/2mm□) | Temperature Difference (°C) |
1 (Example 1) | Ag 70 | 3 | α (Zn-Containing), 3 | None | 12.2 | 0.5 |
2 (Example 2) | Ag 65 | 2 | α (Zn-Containing), 5 | None | 11.8 | 0.4 |
3 (Example 3) | Ag 70 | 3 | β (Zn-Containing), 3 | None | 9.4 | 0.5 |
4 (Example 4) | Ag 70 | 3 | γ (Zn-Containing), 3 | None | 9.8 | 0.5 |
5 (Example 5) | Ag 70 | 3 | δ (Zn-Containing), 3 | None | 10.1 | 0.4 |
6 (Comparative Example 1) | Ag 70 | 0 | α (Zn-Containing), 3 | Confirmed | 5.2 | 0.4 |
7 (Comparative Example 2) | Ag 65 | 0 | α (Zn-Containing), 5 | Confirmed | 4.8 | 0.4 |
8 (Comparative Example 3) | Ag 70 | 0 | Pb-Containing, 3 | Confirmed | - | 0.5 |
9 (Example 6) | Ag 56.6 Pd 10.3 | 2.1 | Zn-Pb Containing | None | 10.0 | 0.5 |
10 (Example 7) | Ag 56.6 Pd 10.3 | 15.1 | Zn-Pb Containing | None | 9.5 | 0.9 |
11 (Example 8) | Ag 56.6 Pd 10.3 | 25.0 | Zn-Pb Containing | Confirmed | 5.8 | 5.0 |
(Note) α: includes 80wt% of zinc boron silicate and 20wt% of Al2O3 β: includes 80wt% of zinc boron silicate, 10wt% of Al2O3, and 10wt% of Cr2O3 γ: includes 90wt% of zinc boron silicate, 5wt% of PbO, and 5wt% of CdO δ: includes 85wt% of zinc boron silicate and 15wt% of Cr2O3 |
As apparent from table 1, in examples 1 to 5,
absolutely no expansion was confirmed and the pattern
formation accuracy was superior. Further, the tensile
strength values were extremely high, each value exceeding
9kgf/2mm□.
In comparison example 3, expansion was confirmed and
the pattern formation accuracy was unsatisfactory. In
comparison examples 1 and 2, although expansion was not
confirmed, the tensile strength was only half of that of the
values of examples 1 to 5. Accordingly, it was proved that
the adding of a small amount of bismuth was extremely
effective for improving the tensile strength.
In example 6, 45 parts by weight of Y2O3 (average grain
diameter 0.4µm), 15 parts by weight of Al2O3 (average grain
diameter 0.5µm), 20 parts by weight of SiO2 (average grain
diameter 0.5µm), and 8 parts by weight of an acrylic resin
binder (manufactured by Mitsui Chemicals, product name: SA-545,
acid number 1.0) were mixed with 45 parts by weight of
silicon nitride powder (average grain diameter 1.1µm).
The mixture obtained in this manner was uniformly
kneaded. The kneaded product was put into a press mold and
pressed to form a plate-like molded product.
Then, after forming holes and performing a drying
process, the molded product was degreased for four hours at
a temperature of 350°C for four hours in a nitrogen
atmosphere to thermally decompose the binder. Further, the
degreased molded body was baked in a hot-press for three
hours at a temperature of 1600°C to produce a silicon
nitride substrate, or the ceramic substrate 9. The pressure
of the hot press was 150kg/cm2.
Then, after cutting the substrate and performing
surface grinding, a paste applying process was performed. In
the process, the noble metal paste P1, the composition of
which is described below, was used and applied to a
thickness of about 25µm to form sample 9. Bismuth oxide was
used instead of bismuth.
The applied noble metal paste P1 was heated at a
temperature of about 750°C for a predetermined time to bond
the wiring resistor 10 and the pads 10a and complete the hot
plate 3 of example 6.
In examples 7 and 8, 0.5 parts by weight of C (carbon)
and 8 parts by weight of an acrylic resin binder
(manufactured by Mitsui Chemicals, product name: SA-545,
acid number 1.0) were mixed with 45 parts by weight of
silicon carbide powder (average grain diameter 1.1µm).
The mixture obtained in this manner was uniformly
kneaded. The kneaded product was put into a press mold and
pressed to form a plate-like molded product.
Then, after forming holes and performing a drying
process, the molded product was degreased.for four hours at
a temperature of 350°C for four hours in a nitrogen
atmosphere to thermally decompose the binder. Further, the
degreased molded body was baked in a hot-press for three
hours at a temperature of 900°C to produce a silicon nitride
substrate, or the ceramic substrate 9. The pressure of the
hot press was 150kg/cm2.
A paste applying process was performed using the noble
metal paste P1 (i.e., pastes A and B), the composition of
which is described below to form samples 10 and 11 (examples
7 and 8).
The same comparison test as that conducted on examples
1 to 5 and comparison examples 1 to 3 was performed on
samples 9, 10, and 11 corresponding to examples 6, 6, and 8.
Expansion of the wiring resistor 10 and the pads 10a was not
confirmed in examples 6 and 7. Further, in example 8, in
addition to the confirmation of the expansion, the
temperature difference in the heating surface was 5°C and
large.
Accordingly, the examples of the present embodiment
have the advantages described below.
The embodiment of the present invention may be
modified as described below.
Spherical noble metal grains may be used in lieu of
the flake-like noble metal grains. Further, instead of using
only one type of the noble metal grains, two or more types
of noble metal grains (e.g., flake-like grains and spherical
grains) may be mixed and used.
The ceramic substrate 9, which is formed from aluminum
nitride or silicon nitride, is not limited to products
manufactured through press molding and may be manufactured,
for example, by performing sheet molding with a doctor blade
apparatus. When performing sheet molding, the wiring
resistor 10 may, for example, be arranged between
superimposed sheets. Thus, the high temperature hot plate 3
is manufactured in a relatively simple manner.
The conductive pattern layer is not limited to the
wiring resistor 10 and the pads 10a used in the above
embodiment and may be other structures such as a conductive
pattern layer that is not a heating resistor.
The noble metal paste P1 need not be screen printed on
the ceramic substrate 9. For example, the noble metal paste
P1 may be stamped on the ceramic substrate 9.
The above oxides do not have to be included in the
noble metal paste P1 separately from glass frit and may be
included in the noble metal paste P1 in a state in which the
oxide is added to the glass frit as a secondary component of
the glass frit. Oxides included in the glass frit as a
secondary component is more preferred since such oxide is
uniformly dispersed in the noble metal paste P1.
Claims (7)
- A hot plate having a ceramic substrate provided with a conductive layer, the hot plate characterized in that the conductive layer includes bismuth or bismuth oxide, glass frit, and noble metal grains.
- The hot plate according to claim 1, characterized in that the content of bismuth or bismuth oxide is 18wt% or less.
- The hot plate according to claim 1 or 2, characterized in that the ceramic substrate is a ceramic nitride substrate or a ceramic carbide substrate.
- The hot plate according to any one of claims 1 to 3, wherein the glass frit includes zinc boron silicate.
- The hot plate according to any one of claims 1 to 3, wherein the noble metal grains is at least one selected from a group consisting of gold grains, silver grains, platinum grains, and palladium grains.
- A conductive paste characterized in that the conductive paste includes bismuth or bismuth oxide, glass frit, noble metal grains, and an organic vehicle.
- The conductive paste according to claim 6, wherein the content of bismuth or bismuth oxide is 18wt% or less.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12697299 | 1999-05-07 | ||
JP12697299 | 1999-05-07 | ||
JP2000126785A JP2001028290A (en) | 1999-05-07 | 2000-04-27 | Hot plate and conductor paste |
JP2000126785 | 2000-04-27 | ||
PCT/JP2000/002873 WO2000069220A1 (en) | 1999-05-07 | 2000-05-01 | Hot plate and conductive paste |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1185144A1 true EP1185144A1 (en) | 2002-03-06 |
Family
ID=26463037
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00922932A Withdrawn EP1185144A1 (en) | 1999-05-07 | 2000-05-01 | Hot plate and conductive paste |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1185144A1 (en) |
JP (1) | JP2001028290A (en) |
WO (1) | WO2000069220A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002082467A1 (en) * | 2001-04-09 | 2002-10-17 | E. I. Du Pont De Nemours And Company | Conductor compositions and the use thereof |
US7157023B2 (en) | 2001-04-09 | 2007-01-02 | E. I. Du Pont De Nemours And Company | Conductor compositions and the use thereof |
WO2009134646A1 (en) * | 2008-04-28 | 2009-11-05 | E. I. Du Pont De Nemours And Company | Conductive compositions and processes for use in the manufacture of semiconductor devices |
TWI477474B (en) * | 2011-07-04 | 2015-03-21 | Hitachi Ltd | A glass composition, a glass frit containing it, a glass paste containing it, and an electrical and electronic component |
DE102015119763A1 (en) | 2015-11-16 | 2017-05-18 | Heraeus Quarzglas Gmbh & Co. Kg | infrared Heaters |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3145389B2 (en) * | 1990-08-05 | 2001-03-12 | 日本山村硝子株式会社 | Heating element |
JP2941002B2 (en) * | 1990-06-02 | 1999-08-25 | 田中貴金属工業株式会社 | Conductor composition |
JPH05114305A (en) * | 1991-10-23 | 1993-05-07 | Asahi Chem Ind Co Ltd | Paste for baking |
JPH08148375A (en) * | 1994-11-18 | 1996-06-07 | Nippon Carbide Ind Co Inc | Conductive paste |
JPH08148030A (en) * | 1994-11-24 | 1996-06-07 | Murata Mfg Co Ltd | Conductive paste |
JP3165396B2 (en) * | 1997-07-19 | 2001-05-14 | イビデン株式会社 | Heater and manufacturing method thereof |
-
2000
- 2000-04-27 JP JP2000126785A patent/JP2001028290A/en active Pending
- 2000-05-01 WO PCT/JP2000/002873 patent/WO2000069220A1/en not_active Application Discontinuation
- 2000-05-01 EP EP00922932A patent/EP1185144A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO0069220A1 * |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002082467A1 (en) * | 2001-04-09 | 2002-10-17 | E. I. Du Pont De Nemours And Company | Conductor compositions and the use thereof |
US7157023B2 (en) | 2001-04-09 | 2007-01-02 | E. I. Du Pont De Nemours And Company | Conductor compositions and the use thereof |
US7914709B2 (en) | 2001-04-09 | 2011-03-29 | E.I. Du Pont De Nemours And Company | Conductor compositions and the use thereof |
WO2009134646A1 (en) * | 2008-04-28 | 2009-11-05 | E. I. Du Pont De Nemours And Company | Conductive compositions and processes for use in the manufacture of semiconductor devices |
TWI477474B (en) * | 2011-07-04 | 2015-03-21 | Hitachi Ltd | A glass composition, a glass frit containing it, a glass paste containing it, and an electrical and electronic component |
TWI567043B (en) * | 2011-07-04 | 2017-01-21 | Hitachi Ltd | A glass composition, a glass frit containing it, a glass paste containing it, and an electrical and electronic component |
DE102015119763A1 (en) | 2015-11-16 | 2017-05-18 | Heraeus Quarzglas Gmbh & Co. Kg | infrared Heaters |
WO2017084980A1 (en) | 2015-11-16 | 2017-05-26 | Heraeus Noblelight Gmbh | Infrared emitter |
US10785830B2 (en) | 2015-11-16 | 2020-09-22 | Heraeus Noblelight Gmbh | Infrared emitter |
Also Published As
Publication number | Publication date |
---|---|
WO2000069220A1 (en) | 2000-11-16 |
JP2001028290A (en) | 2001-01-30 |
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